Irish Water has been forced to monitor the online activity of anti-water charge protesters as demonstrations against workers grow increasingly violent, the Sunday Independent has learned.

The State water company contacted gardai about a series of disturbing messages posted on social media by demonstrators who suggest murdering workers installing meters and burning their vehicles.

In one of the most sinister incidents, protesters caused huge distress for an Irish Water contractor and his family when they branded him a paedophile on Facebook.

Another demonstrator posted instructions for making petrol bombs online in an attempt to encourage attacks on workers.

On the ground, workers have faced violent demonstrations which have seen contractors hit with shovels and pelted with human excrement.

In a statement this weekend, Irish Water said the ultimate cost of the protests will be borne by customers and could lead to higher bills.

The Sunday Independent also understands households that do not have meters installed because of demonstrations may have to wait two years before they can monitor their water usage. This means they will be hit with potentially more expensive assessed charges.

Claims made by contractors injured while installing meters will also add to the rising cost of setting up the new utility company.

In some communities, households have hit back at protesters blocking the installation of meters. Earlier this year, residents in Raheny, North Dublin clashed with demonstrators preventing contractors from installing meters in the area.

"It has been the case that customers want the meter but the protesters are preventing installation," an Irish Water spokeswoman said. The worrying escalation of intimidation against workers is understood to have left many "terrified" and Irish Water intends on pursuing prosecutions against several protesters.

"The protests have been very personal and it has left really big, burly guys in tears," a source said.

"It is a very small minority of people who believe there is no obligation on them to behave appropriately," the source added.

"One guy's picture was put on Facebook and he was called a paedophile. This is a guy with kids." The Sunday Independent understands the picture has since been removed.

Other protesters have encouraged vandalising Irish Water vehicles and faking injury to make claims against the company.

"Personal injury seems to be the way forward, stand stationary get someone to video and the first time that spade hits your shin buckle in two and scream in pain," an online protester wrote on Facebook.

"I'm actually gonna murder the builders putting in them water meters," another wrote on Twitter.

Both incidents have been reported to the Gardai.

Despite the protests, Irish Water is ahead of its installation schedule and currently has more than 350,000 meters in place.

However, contractors hired to install meters have been forced to leave areas because of protests.

In most cases, workers have been able to return to the locations at a later date and complete their work.

However, if an area is deemed unsafe or a phase of installation ends, workers will not return and households face the prospect of not having a meter put in place for another two years. The current phase of installation is due to be completed in 2016.

This would mean the customer will not be able to monitor their water usage and potentially reduce their bill. Instead, they will be charged an assessed rate based on the number of people in a household.

The assessed charge for a family of two adults and two children is €278 a year and bills will begin arriving in October. Once a meter is installed, customers may be entitled to a rebate if they can prove they can save water.

An Irish Water spokeswoman said: "We have temporarily stopped installations in a number of specific areas but have sufficient work in the regions to continue and will be returning to the areas to resume the work in due course, when it is safe for our staff to do so."